Very high speed duplicator with document handling

ABSTRACT

A document handling apparatus for a duplicating machine or copier is disclosed and includes a turnaround roller arranged between an exposure platen for the copier and a document sheet supply tray for directing document sheets fed from the tray back into the tray in an inverted orientation when occasions arise for the inversion. One or more occasions may arise and be initiated automatically depending upon a selected mode of duplication or when an odd number of passes of a document set of sheets are necessary to complete a reproduction run. Other occasions may be operator selected for various reasons such as when pre-printed or pre-punched copy sheets are being processed.

This invention relates to an improved reproduction system having animproved document handling apparatus for use in such system.

With the advent of higher speed and more sophisticated copying machines,considerations as to how the mass of copy sheets generated can best andmost effectively be handled has assumed increasing importance. One wayhas been to provide a reproduction system with an input device in theform of a recirculating document handling apparatus. In this system, adocument sheet is removed from a collated set of document sheets, placedon an exposure platen for exposure at the rate of one exposure for eachdocument sheet, and returned to the top of the set in the documenthandling apparatus until the set of document sheets has been completelycirculated through the apparatus, and a copy set has been produced. Theset of document sheets is then recycled for the reproduction of a secondcopy set, and so on.

After each copy set is produced and collected at a collection station, afinishing device such as a stitcher or stapler is activated to bind theset. These systems are of the pre-collation type wherein the documentsheets are pre-collated in the document handling apparatus prior tocommencement of a reproduction run. The output for the reproductionmachine will likewise be pre-collated in sets corresponding to thesequenced numbered document set in the document handling apparatus. Thecopy sheets are collected in collated sets as they are sequentiallyproduced so that binding may be effected without the interaction ofadditional devices. Such systems are described in U.S. Pat. No.4,134,672.

The disadvantage in these systems having continuous documentrecirculation to produce each bound copy set is that the speed ofproduction is limited to the mechanical limitations in the speed ofhandling document sheets in the document handling device. Itnecessitates that the input device, the document handler, be of extremehigh reliability as it places the original document sheets under thesevere stress of being constantly recirculated. In practice, for thesesystems, there appears to be a threshold in the production rate offinished copy sets. The failure rate in the document handling apparatusincreases beyond acceptable limits when too high a speed of sheetmovement in the apparatus is attempted.

In order to achieve still higher rates of production of finished copysets, various arrangements have been devised, some of which are in themarketplace, which utilize the concept of post-collation rather thanpre-collation. Post-collation systems utilize document handling whereina predetermined number of light images are produced for each documentsheet, say for example, of page one of a multi-page document, before asuccessive document sheet, perhaps page two of the document, is likewiseimaged. This sequencing in turn may be repeated many more times if avery large number of copy sets are to be reproduced. In this manner, themechanical movements involved in document handling are held to aminimum, the parts of the document handler are not subjected to unduewear and the document sheets are handled less frequently. In thesesystems copy sheets are collated in one or more sorter bins for finaluse. In U.S. patent application Ser. No. 180,184 filed Aug. 21, 1980 inthe name of the same assignee of the present application, a singlesorter array is disclosed for collecting copy sets, and a staplingapparatus cooperates with the array to produce fixed copy sets. The binarray or sorter thereby serves as a buffer in the production of stapledcopy sets.

In the post-collation/finishing system however, wherein the documenthandling apparatus is programmed to effect multiple exposures of eachdocument sheet before successive document sheets are exposed, there aresituations during normal use which result in losses of a variable numberof pitches or machine cycles while certain functions must be performedto condition the system for continued operation. For example, at times anumerical sequencing of document sheets must be restored in the documenthandler after a complete cycling of the sheets has left them out ofsequence. This may occur when one is making a copy on paper whichrequires the first image to appear always on the same side of copysheet, such as for punched-hole paper or paper with letterheads, andwhen the reproduction run is running duplex to simplex jobs. Othertimes, when in the duplex mode of operation, while copying duplex toduplex, if there are an odd number of times the documents are circulatedto complete a job. The set of document sheets must be cycled by thedocument handling apparatus, without copying in order to restore the setback into initial sequence preparatory to once again reproducing copies.

Therefore, it is the principal object of the present invention tominimize the number of lost machine time pitches in handling documentsheets during reproduction or copying from duplex document sheets.

Another object of the present invention is to minimize the length ofdocument sheet movement and handling for selected modes of duplication.

These and other objects of the invention are accomplished by utilizing aturnaround roller between an exposure platen and a document sheet supplytray for directing document sheets fed from the tray back into the trayin an inverted orientation when occasions arise for the inversion. Oneor more occasions may arise and be initiated automatically dependingupon a selected mode of duplication or when an odd number of passes of adocument set of sheets are necessary to complete a reproduction run.Other occasions may be operator selected for various reasons such aswhen pre-printed or pre-punched copy sheets are being processed.

A comparison application, filed on Oct. 26, 1981, Ser. No. 314,633 andassigned to the same assignee, discloses and claims a document handlingapparatus having the general horizontal configuration of a documentsheet supply tray, a turnaround roller and the exposure platen for aduplicating machine or copier. The turnaround roller permits return ofdocument sheets to the platen in an inverted orientation to permitcopying of duplex sheets.

Other objects and advantages will be apparent from the followingdescription taken in conjunction with the accompanying drawings,wherein:

FIG. 1 is a schematic representation of an exemplary reproduction systemincorporating the document handling apparatus of the present invention;

FIG. 2 is a schematic view showing details of the document handlingapparatus for the system of FIG. 1; and

FIG. 3 is a block diagram of the controller for the turnaround rollershown in FIG. 2.

For a general understanding of a reproduction machine with which thepresent invention may be incorporated, reference is made to FIG. 1wherein components of a typical electrostatic printing system areillustrated. The printing system is preferably of the xerographic typeas one including a xerographic processor 11, and a document handlingapparatus 12. Preferably the processor 11 is the same as the processorin the commercial embodiment of the Xerox duplicators, modesl 9200 and9400, which utilizes flash, full frame exposure, for very high speedproduction. A document handling apparatus 12 in accordance with thepresent machine is shown in conjunction with the processor 11. Operatingin conjunction with the processor 11 and apparatus 12 is sortingapparatus 13 and thereby forms the reproduction system shown in FIG. 1.

The xerographic processor 11 is arranged as a self-contained unit havingall of its processing stations located in a unitary enclosure orcabinet. The processor includes an exposure station at which an originalto be reproduced is positioned on a glass exposure platen 14 forprojection onto a photosensitive surface in the form of a xerographicbelt 15. The original or set of individual document sheets areselectively transported by the document feed apparatus 12 one documentsheet at a time to the platen 14 for exposure. After a predeterminednumber of exposures of each document sheet is made, the same is returnedto the top of the set until the entire set has been copied.

Imaging light rays from each of the document sheets, which is flashilluminated by an illumination system 18 having suitable lamps 19 areconnected to a suitable flashing circuit (not shown) which is controlledby the programmer for the processor in timed sequence, and in accordancewith the program the operator has preset in the machine. Further detailsin this regard are not necessary since the Xerox 9400 reproductionmachine operates in this manner and is well known. The xerographic belt15 is mounted for movement around three parallel arranged rollers 24,25, 26 suitably mounted in the processor 11. The belt is continuouslyriven by a suitable motor (not shown) and at an appropriate speed. Theexposure of the belt to the imaging light rays from a documentdischarges the photoconductive layer in the area struck by light wherebythere remains on the belt an electrostatic latent image corresponding tothe light image projected fromt the document. As the belt continues itsmovement, the electrostatic latent image passes a developing station atwhich there is positioned a developer apparatus 27 for developing theelectrostatic latent image.

After development, the powdered image is moved to an image transferstation 28 where the developed image is transferred to a supportsurface, normally a sheet of copy paper, brought from a main orauxiliary paper tray 29, 30, respectively, as will appear.

Each sheet is conveyed to the transfer station by a conveyor 31 whichcooperates with sheet registration fingers 32 (only one shown). Thesefingers rotate in a counterclockwise direction, as shown in FIG. 1, andengage the leading edge of a sheet, being adapted to effect the accuratetiming and positioning of a sheet relative to the movement of adeveloped image on the belt 15 and the other timed events inreproduction processing. Further details of the timing relationships andrelated structure and events are described in U.S. Pat. Nos. 3,790,270;3,796,486; and 3,917,396, commonly assigned.

The sheet is moved in synchronism with the movement of the belt 15, andpasses between a transfer roller 33 and the belt 15 at the transferstation. After transfer, the sheet of paper is stripped off the belt 15and transported by a vacuum conveyor 34 in an inverted condition to afusing station where a fuser device 35 is positioned to receive thesheet of paper for fusing the powder thereon. After fusing, the sheet istransported directly to the sorter apparatus 13 for collation if thesimplex mode of reproduction has been selected or to the auxiliary ray30 if the duplex mode has been chosen.

The system comprising the processor 11 and the document handlingapparatus 12 is under control of a programmer P having an operatorcontrol panel which permits an operator various options: to turn theentire system ON or OFF; to program the reproduction system for adesired number of reproductions to be made of each original documentsheet or set; to select whether simplex or duplex copies are to be madefrom simplex or duplex originals to select a desired output arrangement,that is, sets mode or stacks mode, stapled or unstapled; to select oneof a plurality of paper trays; to condition the machine for the type ofdocument, that is, whether one sided or two sided, to select a copy sizereduction mode, and other desirable functions. The programmer P alsoincludes a controller which provides all operational timing andsynchronization between the processor 11 and all of its xerographicprocessing functions, and system control functions, the automatic eventsto be described hereinafter. The controller may include any suitablemicroprocessor having a CPU and the appropriate machine clock, butpreferably the processor is one similar to the Intel 8080 microprocessormanufactured by the Intel Corporation, Santa Clara, Calif., and havingsufficient ROM's and RAM's for all of the necessary functions in thereproduction system.

As previously stated, copy sheets are supplied from either the mainpaper tray 29 or the auxiliary paper tray 30. Main paper tray 29includes a suitable elevator type base 36 on which a supply of sheetsrest, base 36 being supported for automatic up and down movement bysuitable means (not shown). Such movement being arranged to maintain atop-feeding sheet feed mechanism 37 in operative contact with thetopmost one of the sheets on the elevator 36. The sheet feed 37 isoperated intermittently in timed relationship to spacing of images onthe photoreceptor belt 15 under control of the programmer P, and servesto advance the topmost sheet from the supply stack 29 to the main papersupply transport 31.

The auxiliary tray 30, in the exemplary arrangement shown, is arrangedabove main tray 29 and includes an air floatation baseplate 38 uponwhich a supply of sheets may be placed. A bottom-feeding sheet feedmechanism 39 is positioned below the baseplate 38 for feeding sheetsfrom the bottom of the stack of sheets thereon. Assisting in thisfeeding operation is an air floatation system, not shown, whichsubstantially reduces the weight of the stack to permit easy withdrawalof sheets from the bottom. The sheet feed mechanism 39 which isintermittently driven in the same manner as the main tray feed mechanism37, advances one sheet at a time to an auxiliary paper supply transport40. The transport 40 is suitably driven by a drive system (not shown)and is disposed to discharge sheets drawn from auxiliary tray 30 ontothe operating run of main supply transport 31. The sheets from auxiliarytray 30 are thereafter fed to the transfer station. Guides 41 serve tomaintain the sheets in driving contact with the auxiliary paper supplytransport 40 during movement therealong.

The auxiliary tray 30 is of dual purpose. In one, the tray contains asupply of copy sheets to be used while the operator is loading the maintray 29 so as to maintain productivity when the main tray has depletedits supply. In the other purpose, the auxiliary tray 30 is utilized inthe production of duplex copies. In this mode, simplex copies aretransported from the fuser apparatus 35 to the tray 30 for each seriesof exposures for a document sheet, and are transported back again to thetransfer station to receive a toner image on the back side of each ofthe copy sheets in the auxiliary tray. If copying is from simplexdocument sheets, then two document sheets will have been exposed toachieve duplex copy sheets. If a duplex document sheet is to be copied,then both sides of the document sheet would be exposed, eithersequentially or by corresponding stack of the sheets.

During operation, copy sheets leaving the processor 11 after exiting thefuser apparatus 35 are conveyed to an exit slot 50 by way of transports51, 52, if the reproduction system is set for the simplex copying. Ifthe system has been programmed for duplex copying, copy sheets will bedirected to the auxiliary tray 30 as previously stated. If the lattermode of operation is selected, copy sheets conveyed by the transport 51are intercepted by a deflector 54 which is adapted for movement into thesheet path. When the deflector 54 is in the interrupt function, the copysheets are carried around a roller 55 and through the nip formed by thisroller and a cooperating roller 56. The sheet is advanced by rollers 55,56 between an upper sheet guide baffle 57 and a lower sheet guide baffle58 to a second roller pair 59, 60 which further advances the sheet to atransport mechanism 61 which carries the sheet to the auxiliary papertray 30.

When the desired number of one sided copies have been produced anddelivered to the tray 30, the paper handling mechanism for the main tray29 may be inactivated and the paper handling mechanism for the auxiliarytray 30 activated. It should be understood that in following the paperpath around roller 55 and between roller 59, 60 the copy sheets areturned over, i.e. the printed material on the sheets is face up in thetray 30.

Upon re-energization of the system, the sheets from the tray 30 are fedthrough the reproduction machine by means of the feed belt 39 and thetransport 40 for copying on the blank side of the sheet in the samemanner as described heretofore. With the reproduction system beingprogrammed for the duplex mode, and after completion of thecorrespondingly programmed number of one sided sheets, re-energizationof the system also produces the raising of a sheet stop 65 into thepaper path between the upper guide baffle 57 and the lower guide baffle58. The feed roller 59 is mounted with the stop 65 to be raisedtherewith during the phase of duplex copying. In this manner, the feedroller 59 will be displaced away from lower feed roller 60 so thatpapers fed therebetween are not forwarded thereby.

The sheet stop 65 may be formed of a ring-shaped resilient materialbeing compliant enough to resume its circular shape and therebyeffecting the insertion of a sheet into the nip formed between roll 56and a cooperating roll 66, the trailing edge of the sheet being carriedby roll 56 into the nip. The rolls 56 and 66 are formed of a highfriction material to assure positive feeding of a sheet travellingtoward stop 65 and positive feeding of the sheet travelling away fromstop against the drag force generated between two sheets which may be inthe inverter area at the same time travelling in opposite directions.The purpose of the stop 65 and the cooperating action of the rollers56,66 is to invert each copy sheet, while production is in the duplexmode, so that the odd numbered page on a copy sheet reaching the exitslot 50 is face down on the sheet. As will be discussed hereinafter, theinverter 54 and the stop 65 cooperates in various modes of operation.

As shown in FIG. 2, the document handling apparatus 12 serves to feedone document sheet at a time from a supply of document sheets D intocopying position on the platen 14 where a single exposure if only onecopy set is programmed, or a plurality of exposures may be made.Following exposure one or more times, each document sheet isautomatically returned to the document supply and the next documentsheet, if any, is brought into the exposure position on plate 14. Aswill appear, document sheets returned to the supply stack may berecycled by the apparatus 12 or simply removed by the user when thecopying program is completed.

The document handling apparatus 12 includes a sheet support means ortray 70 for supporting document sheets and having a bottom plate 71tilted at an angle with the leading edge of the sheets slightly belowthe main body of the stack of document sheets. The leading edges of thestack D rests against a vertical wall 72 of the tray 70 which is open atits lower end to form an opening 73 through document sheets may projectduring feeding operations.

A document separator feed belt 74 is rotatably supported and drivenaround four rollers 75a, 75b, 75c, 75d positioned below the leading edgeof the stack D so that a portion of the belt 74 is free to extend intothe opening 73 below the bottom document sheets to lift the leading edgeof the stack D. Such lifting action is accomplished by the timing actionof the programmer P which controls rotation of a shaft 78 having a cam79 secured at one end thereof and which serves to periodically rock alever 80. The lever is pivoted at one end at 81 and includes a camfollower 82 cooperable with the cam 79 and the roller 75a at the otherend. The portion of the belt 74 between the rollers 75a, 75b, normallylightly engages the bottom document sheet in the tray 70 so that thebelt slips past the sheet during driving motion thereof in the directionof the arrow.

When the cam 79 rotates its high lobe side against the follower 82, thelever 80 rocks counterclockwise the roller 75a to force the belt 74 infriction engagement with the bottom document sheet to feed the sameforward through the opening 73. This document feed operation drives thedocument sheet along with the belt and between the same and a retard pad85 which is normally in contact with the belt. The pad 85 insures thatonly one document sheet at a time is fed and serves to hold back anyother sheet above the sheet being fed.

The sheet continues to be fed until the leading edge thereof is driveninto the nip of feed roller pair 87, 88 which defines a wait stationwhereat the sheet is held as at this time the roller pair 87, 88 is notin rotation and the cam 79 has moved away from the level 80 to terminateforward feeding of the sheet. A wait station sensor SR-1 senses thepresence of a document sheet and conveys this data to the programmer Pin order to initiate rotation of the roller pair 87, 88 by a suitabledrive thereby.

The resultant drive of the document sheet moves the same across anextended guide plate 90 and below two gates 91, 92 and into the nip ofan on/off drive roll pair 93, 94. The latter roll pair continues movingthe document sheet over the registration member or gate 95 and onto theexposure platen 14 where further movement thereon is pushed up by adocument belt 97. This belt transports the document sheet fully upon theplaten and slightly beyond the edge 98 of the registration gate 97, theedge being slightly above the plate of the platen.

By a suitable program in the logic of the programmer P, the transportbelt 97 is then reversed to produce reverse movement of the documentsheet until the trailing edge thereof abuts the edge 98 therebyeffecting registration of the document sheet. The system logic thenproduces one or more exposures of the sheet until the programmed numberof exposures have been made for that sheet at that time. Upon thisoccurrence, the transport belt 97 commences its reverse drive movementat the same time the registration member 95 has been retracted below theplane of the platen. This activity lowers the gate 98 permitting thedocument sheet to be transported off the platen 14. The registrationgate 95 is movable into and out of registration portion by any suitablemechanism, not shown, which actuation is controlled by the programmer P.In the alternative, the document sheet may be driven off the platen 14by the continuously driven belt 97 working in conjunction with a roller(not shown) positioned between the runs of the belt 97, above the edge98. This roller could be logically controlled to force the lower run ofthe belt upon the document sheet to force the same over the member 95and off of the platen.

As the document sheet leaves the platen area, its movement is picked upby the roller pair 93, 94 now rotating in the reverse direction fromthat which delivered the sheet to the platen area. In leaving the platenarea, the sheet is directed upwardly by the gate 92 which now has beendeflected or turned clockwise about its pivot 99. The sheet is conveyedby the roller pair 93, 94 upon the gate 92 and into the arcuate spacebetween a rotating turnaround drum 100 and a peripheral conforming guideplate 102. A series of rollers 103 extend into this arcuate space to bein contact with the drum surface for transporting the sheet furtheralong the drum. In leaving the platen area, the exiting of the documentsheet is sensed by an exit sensor SR-2 to provide the Programmer withthis data.

As the document sheet is carried around the turnaround drum 100, itreaches a duplex gate 104, pivoted at 105 to be directed thereby eitherback into the tray 70, if simplex documents are being copied, orcompletely around the drum and back onto the platen 14 if duplexdocument sheets are being copied. If the simplex mode has been selected,the gate 104 is rocked in a clockwise rotation to permit a documentsheet to move thereover and into the nip of roller pairs 107, 108 to bedriven thereby into the document tray 70 with the same page orientationas it had before being fed from the tray. This document sheet is soplaced upon the stack of other document sheets to await its turn againto be fed to the platen to be copied as before. A return sensor SR-3senses the return of the sheet as data for the programmer P as part ofthe copy count program.

In any event, if the duplex mode of operation has been selected, theduplex gate 104 is rocked in a counterclockwise rotation to permit thesheet to be driven thereunder and into continued driving movement by aseries of rollers 110. The document sheet once again is driven betweenthe guide plate 90 and below the gates 91 and 92, which have previouslybeen rotated by the machine logic to permit this movement of thedocument sheet. Once again, the sheet is positioned upon the platen 14by the combined action of the on/off drive roller pair 93, 94 and thetransport belt 97. In this sequence however, the document sheet had beeninverted to bring the other side thereof (side two, or even side) uponthe platen for copying.

Assuming that the odd side of the sheet, say page 1, was the first sidecopied in the previous copying exposures, now page two is upon theplaten for copying exposures. After the programmed number of exposureshave been completed, the document sheet is returned to the tray 70 aswas the case for a simplex document sheet as described above. In thiscase however, the even side of the sheet, or page two, becomes orientedin the tray face down. It will be seen then that for a set of duplexdocument sheets being copied in this manner, the even sides of thesheets would all be oriented in the face down position, so that the traywill not present the proper sequence of papers in a document set.

As will be seen later in the description of the duplex-to-duplex mode ofoperation, another pass of the set of document sheets, the second pass,will restore the numerical sequence of the document sheets and all othereven-numbered passes will do likewise. In order to reorient thenumerical sequence of document sheets immediately without anothercopying pass, the set of sheets must be circulated individually aroundthe turnaround drum 100 in order to place the odd numbered documentpages in the face down position. In these positions, the document sheetsin a set are disposed for recirculation into copying position. There-orientation is under control of the programmer P after the returnsensor SR-3 has indicated that a document sheet has been returned to thetray 70, presumably the last sheet, and this data is compared to thenumber of document sheets in the set. With this arrangement, maximumthroughput is achieved and only one machine pitch or copy cycle is lostduring a change in document sheets. This is accomplished by timingevents so that a document sheet is travelling over the drum 100 on itsreturn to the tray 70 while another document sheet is being placed onthe platen 14 from below the drum.

Circulation of the document sheets around the turnaround drum 100 forre-orienting the same, as described in the preceding paragraph iseffected by programmed rotation of the gate 91 about its pivot axis 113.When this circulation procedure has been activated, document sheets arebottom fed from the tray 70, as was the case during the ordinary copyingmode of operation, by the now actuated feed belt 74 working inconjunction with the retard pad 85. The sheets are transported by theroll pair 87, 88 to across the arcuate top surface of the gate 91,previously pivoted in a counterclockwise direction to permit thisdeflection. During this operation, the function of the wait stationsensor SR-1 and the on/off operation of the roll pair 87, 88 isinhibited in order to permit very rapid circulation of the documentsheets from the tray 70, around the turnaround drum 100 and back intothe tray in the shortest time possible in order to minimize loss ofproductivity. At the termination of this circulation of document sheets,as determined by the sensing of the last sheet by the return sensor SR-3when compared to the document sheet count, the document handlingapparatus 12 is again ready for another cycle of copying. Thisoccurrence may be determined in the machine logic so as to commencecycling automatically in the event the operator has preset theprogrammer P to produce copy sets greater than the number producedduring the first cycling of document sheets. In any event, after thedocument sheets have been re-oriented, the gate 91 is rocked to itsnormal position as shown in FIG. 2 preparatory to another copying cycle.

For each complete cycling of the apparatus 12, and correspondingproduction of copy sheets, the bins 120 of the sorter 13 will receivethe copy sheets as collated sets. As shown, the sorter comprises twosorter modules 121, 122, each having twelve bins. With the documentapparatus 12 being programmed to effect the production of twelveexposures for each document page placed on the platen 14, the firstseries of copying exposure will produce corresponding twelve copysheets. If the simplex mode of operation has been selected, the twelvecopy sheets will be transported one sheet each to the bins of the uppersorter module 121. If the duplex mode has been selected, the twelve copysheets are conveyed to the auxiliary tray 30 to await the inverting ofthe document sheet by the turnaround drum 100 and associated structureso as to produce copies indicative of the other side of the documentsheet. Upon completion of the duplex copy sheets, these are transportedto the upper sorter module, one to each bin. This process repeats untilthe document set has been cycled and corresponding copy sets have beencollated. If more than twelve copy sets have been programmed forproduction, the lower sorter module 122 will be utilized to collate theremaining copy sets up to twelve sets if twenty-four or less copy setshave been programmed.

While the number twelve has been described for the number of sorter binsper module and the number of exposures per document page, it will beunderstood that any other matching number may be utilized. It will alsobe understood that another form of output for the processor 11 andapparatus 12 may be utilized instead of the sorter 13. For example, astapling or stitching apparatus may be coupled to processor, such as thearrangement disclosed in the above-referred to U.S. patent applicationSer. No. 180,184.

It will be appreciated that the foregoing described reproduction systemcomprising the processor 11, the document handling apparatus 12 and theoutput section 13 in the form of sorter modules, is arranged forproducing copies of documents in all of the four modes of input/outputmodes of operation, that is (1) from simplex documents to simplexcopies, (2) from simplex documents to duplex copies, (3) from duplexdocuments to simplex copies, and (4) from duplex documents to duplexcopies.

In the first mode of operation, simplex to simplex the document sheetsare individually applied to the platen 14 and exposed a predeterminednumber of times, in multiples of twelve exposures. As each documentsheet is exposed on the side carrying information being copied, it isreturned directly to the tray 70 by way of the gate 92, the spacebetween the drum 100 and guide 102, over the gate 104 and into the tray70. Copy sheets are fed from the main tray 29, are processed, andtransported directly out of the exit slot 50 to the sorter modules. Theauxiliary tray 30 is not utilized and the inverter gate 54 is positionedout of the path of movement of the copy sheets to the exit slot.

In the second mode of operation, simplex to duplex, the document sheetsare handled as in the simplex to simplex mode. In this mode, however,the inverter gate 54 is deflected downwardly to intercept copy sheetsbearing page one, or the odd numbered pages to direct the same into theauxiliary tray 30. Since copy sheets bear images face down through theprocessor 11, the blank sides of copy sheets will be face down in thetray 30. As will be understood, pairs of successive document sheetsbeing presented to the platen 14 for exposure will provide thecorresponding two side copies on the copy sheets.

After the predetermined number of exposures have been made for the oddnumbered side of a document sheet, the copy sheets bearing the oddnumbered pages face up in the tray 30 are fed from the tray to beprocessed again on the face down blank side to receive the even numberedpage. Since the copy sheets bear face down even pages, they must beinverted before being inserted into the sorter bins in order to maintainnumerical sequence. To accomplish this inversion, the stop member 65 israised into the path of sheet movement to the tray 30 and the invertergate 54 is lowered to intercept copy sheets leaving the fuser 35. Theduplex copy sheets, with even numbered pages face down, are therebyinverted so that they leave the exit slot 50 with odd pages face down.In this manner, as the copy sheets are being collated in the sortermodules, they will appear in proper numerical sequence.

In the third mode of operation, duplex originals to simplex copies, thedocument sheets are handled as previously described with the alternateturnaround function of the drum 100 and with the proper sequencing ofthe gates 91, 92 and 104. As in the previous modes of operation, thedocument sheets are face down in the tray 70 at the start of areproduction run, that is, odd page numbers face down and even numberedpages are face up. In this mode of operation, the turnaround drum 100path is utilized twice during each pass, that is, to place side two onthe platen after imaging side one and then to restore the initial orderof the originals before returning the document to the tray 70.

In starting a run, the first document sheet is brought to the platenwith its odd page face down and exposed the predetermined number oftimes, which our example is twelve exposures. The resultant copy sheetsare transported to the sorter 13 for sorting by way of transports 51,52. After the twelfth exposure, the document sheet is removed from theplaten, diverted around the turnaround drum 100 and sent back to theplaten with the even numbered page face down. After twelve exposures ofthis page, the resultant copy sheets are transported to the sorter forsorting. After the predetermined number of exposures have been made, thedocument sheet is again diverted around the drum and sent back to theplaten. However, it is immediately removed therefrom and carried aroundover the drum and back to the tray 70. In this manner, the originalorder of the document sheets is restored. This procedure results in theskipping of three machine pitches between document sheet changeshowever, in this sequence of operation, twenty-four copies have beenproduced, twelve copies of each side of the document sheet. Since thisprocedure is a simplex copy mode, neither the inverter gate 54 nor thestop 65 are inserted into the processor paper path for any portion ofthe copying operation.

In the fourth mode of operation, duplex originals to duplex copies, ifthe number of passes of the complete set of document sheets is odd, oneadditional pass is required, without imaging, at the end of thereproduction run to restore the initial sequence of the document sheets.

In starting a run, the first document sheet is transported to the platenodd face down and exposed the predetermined number of times. Theresultant copies are transported to the auxiliary tray 30 for furtherprocessing. After the last exposure for each document sheet, the sheetis removed from the platen, diverted to the turnaround drum 100 by thegate 92 and, with the gate 104 pivoted upwardly and the gate 91 in itsclockwise position, the sheet will be returned to the platen with theother side of the sheet (even number) down. After twelve exposures ofthe even-numbered side the document sheet is again removed from theplaten, but now the gate 104 is rotated to permit the return of thesheet to the tray 70. With this return, the even side is face down inthe tray as well as all other document sheets in the set being copied,that is, the sheets will be sequenced with all even numbered pages facedown. Although the order of the sheets remains unchanged during handlingand copying, the sequence of the document sheets is altered by aninversion of each document sheet during each pass of the set through thedocument handling apparatus. The initial sequence of the document sheetsis restored at the completion of each of the even numbered passes, i.e.Pass 2, 4, 6, 8, etc.

For production runs which require an odd number of passes, the initialsequence is restored at the end of the run by cycling the sheets throughthe document handling apparatus as before but without exposing thesheets. During an even pass through the document apparatus, tocompensate for the inversion created by the previous pass, copies of theeven document sheets are made during side one copy processing in theprocessor 11, and copies of the odd document sheets are produced duringside two copy processing. Since the sequence of document sheets and thecopy destination of a document sheet is dependent upon the documentapparatus pass number, it is necessary that the inverter gate 54 andstop 65 respond to select the appropriate paper path.

As previously stated, the turnaround drum 100 may be utilized to restorethe numeral sequence of page numbers of the document sheets of a setafter each pass of the set upon the platen for copying depending uponthe desires of the operator. A suitable control switch (not shown) maybe utilized to instruct the machine logic for this selectable feature.Otherwise, the sequence will be restored automatically during areproduction run of many passes for each even numbered passes orrecirculation of a document set.

The drum 100 may be selectively utilized for other purposes whereindocument sheets are not transported to the platen in order to maintainnumerical sequence of the document sheets. One such purpose wouldinvolve copy sheets having pre-printed letterheads or are pre-punched.In the duplex to duplex copy mode, copy images are inconsistent withsheet orientation for copies produced during the even passes. Tomaximize throughput during this copy mode, the foregoing description ofmethod of operation has been to copy side 2 of each duplex documentsheet first on the even numbered passes. This method of operation issatisfactory for plain copy sheets, but is inconsistent for pre-orientedcopy paper. For example, the pre-punched holes end up on the wrong edgefor copies made during the even numbered passes and letterheads end upon side 2 of the copy sheets. The only solution to this problem, ofcourse, at the sacrifice of throughput is to re-invert document sheetsas previously described after each pass when making copies.

Two other situations may arise wherein document sheets must bere-inverted without making copy. As described above, re-inversionwithout copying may be achieved either by bringing each document sheetto the platen and to return the same over the drum 100, or by the morepreferred and faster method of utilizing the gate 91 to direct documentsheets around the drum 100 and back to the tray. In one of thesituations, re-inversion occurs after each pass when making simplexcopies of duplex document sheets, and in the other situation,re-inversion occurs after the last pass in the normal duplex to duplexmode making copy on plain paper (non-oriented), when the lastpreselected pass is an odd-numbered pass.

For example, while the foregoing description of operation isspecifically directed to the handling of document sheets face down, thatis, with page one of the first sheet of the document set at the bottomof a stack, and the last page of the set on the top, it will beunderstood that the reverse of this sequence may be handled by theforegoing-described apparatus. With the sequence of document sheetsarranged with page one at the bottom of the stack, as in the foregoingdescription, the sorter bins in the sorter 13 must be arranged so thatthe copy sheets come to rest with page one on the bottom of each bin andall subsequent sheets become collated with their odd numbered pagesfacing downwardly. In the reverse sequence of the document set, that is,with page one of the first sheet on top of the stack, and the last pageat the bottom, the sorter bins must be rotated so that the copy sheetscome to rest with the page indicative of the last document sheet firstentering a bin, and all subsequent copy sheets become collated withtheir even numbered pages facing downwardly. In either arrangement ofdocument sheets, they are nevertheless arranged in sequential order.

The block diagram FIG. 3 illustrates the relationship between inputs andoutputs for the document handling apparatus in the foregoing descriptionand the control arrangement therefor. While not shown as beingunnecessary, the inputs and outputs for the processor 11 are alsointerrelated to the control arrangement. The block diagram also depictsthat if a sorter is being utilized, the sorter typically includes gatesolenoids, one for each bin, which are actuated, as an output, in timesequence if copy sheets are to be collated in the sorter. Other outputswould include copy sheet feed actuation, illumination flashes and so on,proper functions of the processor 11.

Therefore, while the invention has been described in connection withparticular arrangements and operations thereof, no limitation isintended thereby except as defined in the following claims.

I claim:
 1. In a reproduction machine having a document handlingapparatus for feeding document sheets individually from a stack to anexposure platen for the machine and return to the stack for selectiverepeated copying of one side only or both sides of the document sheets,with the sheets in the stack being arranged in sequential order, andwherein the apparatus includes the improvement comprising:a documentsupport member adjacent to one side of the platen for supporting thestack, said support member having means for feeding each document sheetfrom the bottom of the stack associated therewith, means defining asheet path from the document sheet feed means to the platen withoutinverting the sheet, means defining a sheet path from the platen forinverting the sheet and to return the sheet to the platen in an invertedorientation thereby presenting the first side of the sheet for copying,deflector means being movable to an operative position for directing thedocument sheet from said support member to the platen or movable toanother operative position to return the sheet to the top of the stackin an inverted orientation, and control means for selectively actuatingsaid deflector means to either of said operative positions.
 2. In areproduction machine having a document handling apparatus for feedingdocument sheets individually from a stack to an exposure platen for themachine and return to the stack for selective repeated copying of oneside only or both sides of the document sheets, with the sheets in thestack being arranged in sequential order, and wherein the apparatusincludes the improvement comprising:a document support member adjacentto one side of the platen for supporting the stack, said support memberhaving means for feeding each document sheet from the bottom of thestack associated therewith, means defining a sheet path from thedocument sheet feed means to the platen, means defining a sheet pathfrom the platen for inverting the sheet and to return the sheet to theplaten, deflector means being movable to an operative position fordirecting the document sheet from said support member to the platen ormovable to another operative position to return the sheet to the top ofthe stack in an inverted orientation, and control means for selectivelyactuating said deflector means to either of said operative positions. 3.In a reproduction machine having a document handling apparatus forfeeding document sheets individually from a stack to an exposure platenfor the machine and return to the stack for selective repeated copyingof one side only or both sides of the document sheets, with the sheetsin the stack being arranged in sequential order, the improvementcomprising:a document support member adjacent one side of the platen forsupporting the stack, means for separating a sheet from the bottom ofthe document sheet stack and feeding the same to the platen, means forremoving the sheet from the platen and directing the same to return thesheet to the platen, and guide means arranged to receive each sheetafter the same has been separated from the sheet stack and to guide thesame back to the top of the stack thereby inverting the sheets in thestack.
 4. A document handling apparatus for feeding document sheets froma stack onto a platen of a copier machine for exposure thereof and toreturn the sheets to the top of the stack comprising:a tray forsupporting the stack of document sheets being positioned on one side ofthe platen, means for feeding each document sheet seriatim from thebottom of the stack along a feed path and to transport the same onto theplaten for exposure thereon, said means for feeding being adapted totransport each document sheet from the platen to the top of the stack inthe tray along a return path, turnaround roller means arranged betweenthe platen and said tray and with a portion of said feed path arrangedadjacent a section of the periphery thereof and with a portion of saidreturn path adjacent another section of the periphery, first deflectormeans arranged between the platen and said roller means and beingactuable to a control position for permitting the sheets to be directedto the platen and to another control position for diverting sheetsreturning from the platen to said return path, and second deflectormeans arranged between said tray and said roller means for directingsheets fed from said tray around said roller means and back into saidtray in an inverted orientation.
 5. The document handling apparatus ofclaim 4 wherein said portion of said feed path and said return path arediametrically opposed relative to said roller means.
 6. In the method ofcopying both sides of duplex document sheets arranged in a stack, withthe sheets in the stack being arranged in sequential order, theimprovement comprising:supporting the stack of document sheets adjacentone side of the exposure platen of a copier, and selectively:(a)1.separating each document sheet from the stack and feeding the same tothe platen,
 2. removing the sheet from the platen, along a path forinverting the same and returning the sheet to the platen, and 3.removing the sheet from the platen a second time and directing the sheetto the top of the stack in its original orientation, or (b) separatingeach document sheet from the stack, by-passing the platen and returningthe same to the top thereof in an inverted orientation.
 7. In the methodof copying of both sides of duplex document sheets arranged in a stack,with the sheets in the stack being arranged in sequential order, theimprovement comprising:supporting the stack of document sheets adjacentthe exposure platen of a copier, separating the bottom sheet from thestack and feeding the sheet to the platen in a first direction, removingthe sheet from the platen along a path in a direction opposite saidfirst direction and returning the sheet to the platen in an invertedorientation, removing the sheet from the platen a second time in saidopposite direction and directing the sheet to the top of the stack, andseparating the bottom sheet from the stack bypassing the platen andreturning the sheet to the top of the stack in an inverted orientation.